不同加载速率下汽轮机转子钢的高温低周疲劳断裂特征
Fracture Characteristics of High Temperature and Low Cycle Fatigue of Turbine Rotor Steel at Different Loading Rates
何建军, 陈 荐, 孙清民, 邱 玮
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作者单位：(长沙理工大学 能源与动力工程学院 能源高效清洁利用湖南省高校重点实验室, 湖南 长沙 410076)
中文关键字：低周疲劳； 断裂； 裂纹； 加载速率； 汽轮机转子
英文关键字：low cycle fatigue; fracture; crack; loading rate; turbine rotor
中文摘要：采用RDL05电子蠕变疲劳试验机，在0.5 × 10-2、0.1 × 10-2 s-1两种加载速率条件下，对30Cr1Mo1V汽轮机转子钢进行高温低周疲劳试验，用带有能谱分析的JSM-5610扫描电镜分析试样的断裂特征。结果表明，试样断面有裂纹起源区、裂纹扩展区和瞬断区，瞬断面与其他两区呈一定角度的剪切唇；裂纹源区比较平坦，细小裂纹沿晶界萌生于材料内部；断裂类型主要为沿晶断裂，在0.1 × 10-2 s-1时裂纹数目较少；在瞬断区以韧窝为主要断裂特征，并有少量疲劳条纹，0.5 × 10-2 s-1时韧窝较深；从试样表面萌生的裂纹可看出，裂纹附近出现了大量尺寸在5～30 μm的鱼卵状裂纹珠，这是由于高温氧化、疲劳载荷交互作用形成的。
英文摘要：High temperature and low cycle fatigue experiments of the turbine rotor 30Cr1Mo1V steel were carried out using RDL05 creep fatigue electronic test machine at loading rate of 0.5 × 10-2 s-1 and 0.1 × 10-2 s-1. The fracture characteristics of the specimens were studied using JSM-5610 scanning electronic microscope (SEM) with an energy dispersive spectroscope (EDS). The results show that the fatigue crack initiation area, fatigue crack propagation area and the fatigue fracture area can be obviously observed, there is a shear lip with a certain angle of the other two areas. The crack initiation area is relatively flat and the fine fatigue cracks are initiated from the grain boundaries in the inner materials. The dominant fracture behavior is intergranular fracture and the number of fatigue crack is relatively scarce in the specimen at the loading rate of 0.1 × 10-2 s-1. The chief fracture characteristic is dimple and a small amount of fatigue striations, and the dimples are deeper in the specimen at the loading rate of 0.5 × 10-2 s-1. The area near the fatigue cracks initiating from the surface of the specimens emerges a great amount of fish eggs-like crack beads with the size of 5～30 μm, which are formed by high temperature oxidation and fatigue load interaction during the high temperature and low cycle experiment.